Hydraulic ram



1949 J. A. CELENZA 2,487,920

HYDRAULIC RAM Filed May 25, 1948 2 Sheets-Sheet 1 INVEN TOR.

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Patented Nov. 15, 1949 2,487,920 HYDRAULIC RAM John A. Celenza, Cleveland, Ohio Application May 25, 1948, Serial No. 29,185

4 Claims. (01. 121 4e) This invention relates to improvements in hydraulic cylinders, and more particularly to a novel double-acting hydraulic cylinder of the type having telescopic pistons, the primary object of the invention being to provide a more compact and efi'icient arrangement of this kind which is of mechanically superior construction, and which can be manufactured in a serviceable and rugged form at relatively low cost, and which is adaptable for hydraulic rams of different kinds or in any machine wherein a comparatively heavy pressure and reciprocating motion are required,

along with a relatively long power stroke.

Other important objects and advantageous features of the invention will be apparent from the following description and accompanying drawings, wherein merely for purposes of illustration, 2. specific embodiment of the invention is set forth in detail.

In the drawings:

Figure 1 is a side elevation of said embodiment with the telescopic piston retracted,

Figure 2 is a top plan view thereof,

Figure 3 is a transverse vertical section taken on line 33 of Figure 1,

Figures 4 and 5 are horizontal sections taken on lines 4-4 and 5-5, respectively, of Figure 1,

Figure 6 is a transverse vertical section taken on line 66 of Figure 2, showing the telescoped pistons extended,

. Figure 7 is a transverse vertical section similar to Figure 6, showing the inner piston of the inner cylinder extended and the inner cylinder retracted,

, Figure 8 is a horizontal section taken on the line 8-8 of Figure 1, and

Figure 9 is a vertical sectional detail, showing Referring in detail to the drawings, the letter A generally designates theouter cylinder comprising the barrel II, the upper and lower relatively heavy heads l2 and 29, respectively, the facing sides of the heads being formed with grooves l4,

14 receiving the barrel ends, and the bolts l5 which assemble the heads on the barrel, the lower ends of the bolts being threaded at It into the lowerhead and the upper ends of the bolts extending through the upper head and provided on their upper ends with tightening nuts IT.

The upper head I2 is provided with a fluid passage l8 opening through the edge thereof and terminating at l9 at the center of the head. The lower head 29 is formed, as particularly clearly shown in Figure 8, with an annular chamber or ,passage 22,, which has a reduced radial passageor 5 5 port 23 leading from one side thereof through the edge of the head. The annular passage 22 is in the nature of a groove formed in the sidewall of the axial bore 24 formed in the lower head 29.

The upper end of the bore 24 has a slightly enlarged diameter upper portion 25 opening into the annular passage 22, whereby constant communication is provided between the passage 22 and the space existing between the interior of the outer cylinder barrel II, and the inner tubular piston B, which slides in the bore 24.

The inner piston B comprises a tubular body portion 21 slidably fitting the lower cylinder head bore 24 and a larger diameter head portion 28 at its upper end which slidably engages the bore of the cylinder barrel II. The lower part of the inner cylinder B includes a solid portion [3 provided with an axial squared bore 30 slidably accommodating the squared shaft on piston rod 3| on whose upper end is fixed a solid, relatively heavy, piston 32 working in the bore 33 of the inner cylinder B. The upper end of the squared bore 30 is enlarged to accommodate shaft packing 33. The shaft 3| has an external cross pin 3! arranged to abut the underside of the solid portion l3 of the inner cylinder to limit upward travel of the piston 32 to a point close to the upper head l2 of outer cylinder A.

The heavy lower portion I3 of the inner cylinder B is formed at the side opposite the port 23 of the lower head 29 of the outer cylinder A, with a reclining T-shaped passage, including the standard portion 34 which registers with the annular passage 22 only in the retracted position of the inner cylinder B, as shown in Figure 3, the branch 35 which opens through the top of the solid portion l3 to communicate with the interior of the tubular inner cylinder B, and the branch 36 which opens through the bottom of the solid portion l3. Communication between the interior of the inner cylinder B and the annular passage 22, through the passage branch 35 and standard portion 34, is normally out 01f by a check valve, including a ball 31 urged into blocking relation to the passage portions 35 and 34 by ,a concaved block 38 pressed against the ball by a spring 38' compressed by a screw plug 39 threaded in the passage branch 36.

The opposite side of the solid portion [3 of the inner cylinder B is formed with an inverted T-shaped passage, including the vertical branch 40 opening through the top of the solid portion l3 and the horizontal branch 4| opening through the side of the portion I3 and adapted to register with the annular passage 22, only inthe retracted position of the inner cylinder B, as shown in Figure 3. The passage branch 4| is augmented by a valve seat 42 set into the side of the portion 13 for accommodating a ball check 43 pressed thereagainst by a concaved block 44 by a spring 44 in the passage branch 4|, thereby cutting oil communication between the interior of the inner cylinder B and the annular passage 22 during application of fluid pressure through the port l8 for expanding the device. When for contracting the device fluid pressure is applied through the port 23 the ball check 43 yields to pass fluid under pressure into the interior of cylinder B for driv ing the piston 32 upwardly therein.

In a position at 90 from these, passag the outer piston solid portion I3 is formed in its side with a radial recess 45 containingan expanding spring 46 behind a latch 41 having a notch 48 in the lower side of its outer end for engaging a retainingv plate 49 1ocated thereund r, in th manner shown in Figure 9. The latchi's arranged to engage in the annular passage 22, in the re.- tracted; position, of the inner cylinder B, so as to retain the same in such'position until its latch 41: is retracted by descent of the latch pin 56, depending from the solid piston 32", as the solid piston 32 moves downwardly toward the fully extended, position shown, in Figure 7., The lower end of the. latch, pin 50 has acam face 5| arranged to engage the inner side of an opening 52 in the. latch, as the latch pin moves downwardly through an access opening 5.3 in the solid portion l3, in a manner to retract the latch 41 in a radially inward direction. as shown in Fig;- ures 6 and 7, wherein. the latch 41 is out of en.- gagement withthe annular passage 22 so that the inner cylinder B can move downwardly-toward the. extended position, shown in Figure 6. On upward return movement of the inner cylinder B, engagement of the cam surface 54' on the latch 41 with the underside of the lower head 29., of the outer cylinder A retracts the latch 41 sufficiently to permit the inner cylinder B to pass upwardly freely toits retracted position.- However, under ordinary conditions of operation, wherein the inner piston 32 is first fullyextended, followed by the inner cylinder B, the inner piston 32 will have the latch pin 56 in continuous engagement with the latch 41 in a manner to hold the latch in retracted position during retracting movement of the inner cylinder B, the main function of the latch arrangement being to prevent the inner cylinder B from moving toward extended position until theinner piston 32 has first been fully extended from the inner cylinder B.

To extend the telescopic piston assembly from the retracted position shown in Figure 3, fluid under pressure is injected throughthe passage 18 in the upper head 12 of outer cylinder A, whereby the inner piston 32 and its rod or shaft 3|, is moved downwardly the required distance. If a greater extension of the piston assembly is wanted than is afforded by extension of the inner piston 32 alone, injection of the fluid is continued until the inner piston 32 reaches bottom position, wherein its latch pin 50' retracts the latch 41. As the inner piston 32 moves downwardly, the space in the inner cylinder B being full of fluid, fluid isforced'throu-gh the branch 35, 34 of the reclining T-shaped passage in the solid portion l3, into the space 2 existing between the outer cylinder barrel I' l and the inner cylinder barrel 2?, the ball check 31'being unseated in the process, and the ball check 43 in the inverted T-shaped passage holding closed,

and the annular passage 22 being filled with fluid from the reclining T-shaped passage, so that fluid is exhausted through the port 23 in the lower head 29 of the outer cylinder A back to the hydraulic system (not shown).

As the latch 41 is retracted and the inner cylinder B is thereby freed to move out of cylinder A, and injection of fluid under pressure is continued through the port. I& inthe upper head I2 of outer cylinder A, the pressure on the inner piston 32 forces the inner cylinder B downwardly the desired distance or to the fully extended position shown in Figure 6, if desired, in which the piston head 28 engages the lower head 29 of the outer cylinder A. In the downward movement of the inner cylinder B the head 28 forces the fluid in the space 2t, existing between the cylinders A and B, through the annular opening 25 into the annular passage 22 and then out of the port 23, in the lower head 29 of. cylinder A back to the hydraulic system.

To retract the piston assembly, fluid pressure is. exerted through, the port- 23 in the lower head 29 of outer cylinder A, with the port H3 in the upper head 12 of cylinder- A acting as exhaust. With the piston assembly inthe fully extended position shown inFigures 6 and '7, the fluid under pressure coming through the lower port 23 fills the annular passage 22 and acts upwardly'ag'ainst the underside of piston head 28, thereby filling the. space 2| existing between the cylinder barrel fl and the outer cylinder body 21. This causes the inner cylinder B to rise and to continue rising in. the outer cylinder A until the piston head 28 engages the upper head I2 of outer cylinder A, and the latch 41' re-engages in the annularpas- Sage 22, asshown in Figure '2. p 7

The space 2 l existing between the cylinder barrels H and 21 then being fllled with fluid, as well as the annular passage 22, further injection of fluid under pressure through the lower port 23 exerts pressure against the bottom of the inner piston 32 through the branch 4ll'of the inverted T-shaped passage, thereby causing the inner piston 32 to rise in the inner cylinder B until the piston 32 approaches the upper head I2 of outer cylinder A and is stopped close thereto by engagement of the shaft cross pin 31" with the underside of the solid lower portion $3 01 the inner cylinder B. In all of the upward or retracting movement of the inner cylinder B and the inner piston 32 the fluid displaced thereby is exhausted through the upper port [8 in the upper head 12 of the outer cylinder A. V

In anapplication of the above described device, the plate l2 may be attached to orabutted against a stationary part of a mechanism, and, as shown in Figure 6, the threaded end 56 of the piston rod 30 may be threaded into a movable part 51- of the mechanism whereby: the device is connected to reciprocate or merely to spread the parts relative to each other.

What I' claim p l. A hydraulic cylinder comprising a cylinder barrel having upper and lower cylinder heads, an outer piston comprising a tubular body smaller in diameter than said barrel and concentrically spaced therefrom, an enlarged tubular head on the upper end of said tubular body working in said barrel, and a solid portion on and closing the lower end of said tubular body, an inner piston working in said tubular body and tubular head having a shaft working through an accommodatlng opening formed in said solid portion of said outer cylinder, said upper cylinder head being formed with afluid port opening into the upper end of said tubular body, said lower cylinder head being formed with a fluidport arranged to have communication with the space between said tubular body of said outer piston and said cylinder barrel below said outer piston head and with solid portion of said outer piston and said inner piston, said upper and lower ports being arranged to alternate as fluid injection and fluid exhaust ports, with said upper port acting as injection port, and said lower port as exhaust port while said outer and inner pistons are in their elevated retracted positions, for driving said pistons downwardly toward their extended positions, and said lower port acting as injection port and said upper port as exhaust port for driving said pistons upwardly from downwardly extended positions toward retracted positions, normally en aged latch means operating between said outer piston and said lower cylinder head for locking said outer cylinder in its retracted position while said inner piston is in a retracted position and until said inner piston is moved to its extended position from a retracted position, and latch operating means on said inner piston for releasing said latch means as said inner piston reaches its extended position.

2. A hydraulic cylinder comprising a cylinder barrel having upper and lower cylinder heads, an outer piston comprising a tubular body smaller in diameter than said barrel and concentrically spaced therefrom, an enlarged tubular head on the upper end of said tubular body working in said barrel, and a solid portion on and closing the lower end of said tubular body, an inner piston working in said tubular body and tubular head having a shaft working through an accommodating opening formed in said solid portion of said outer cylinder, said upper cylinder head being formed with a fluid port opening into the upper end of said tubular body, said lower cylinder head being formed with a fluid port arranged to have communication with the space between said tubular body of said outer piston and said cylinder barrel below said outer piston head and with the space within said tubular body between said solid portion of said outer piston and said inner piston, said upper and lower ports being arranged to alternate as fluid injection and fluid exhaust ports, with said upper port acting as injection port and said lower port as exhaust port while said outer and inner pistons are in their elevated retracted positions, for driving said pistons downwardly toward their extended positions, and said lower port acting as injection port and said upper port as exhaust port for driving said pistons upwardly from downwardly extended positions toward retracted positions, a chamber formed in said lower piston head communicating with said lower port and having restricted communication with the space between said cylinder barrel and said tubular body of said outer piston below the head, first and second passage means formed in said solid portion extending between said chamber and the interior of said tubular body of said outer piston, and first and second check valves in said first and second passage means, respectively, said first check valve being arranged to be closed while said second check valve is open and said second check valve open while said first check valve is closed depending upon said pistons being in retracted or extended positions and fluid being injected through said upper port or said lower port, said first and second passage means having communithe space within said tubular body between said 6 cation with said chamber only while saidouter piston is in its fully retracted position.

'3. A hydraulic cylinder comprising a cylinder barrel having upper'and lower cylinder. heads, an outer piston comprising a tubular body smaller indiameter than said'barrel and concentrically spaced therefrom, an enlarged tubular head on the upper end of said tubular body working in said barrel, and a solid portion on and closing the lower end of said tubular body, an inner piston working in said tubular body and tubular head'having a shaft working through an'accommodating opening formed in said solid portion of said outer cylinder, said upper cylinder head being formed with a fluid port opening into the upper end of said tubular body, said lower cylinder head being 'formed with a fluid port arranged to have communication with the space between said'tubular bodyof said outer piston and said cylinder barrel below said outer piston head and with the space within said tubular body between'said solid portion of said outer piston and said inner piston, said upper and lower ports being arranged to alternate as fluid injection and fluid exhaust ports, with said upper port acting as injectionport and said lower port as exhaust port 'while said outer and inner pistons are in their elevated retracted positions,

for driving said pistons downwardly toward their extended positions, and said lower port acting as injection port and said upper port as exhaust port for driving said pistons upwardly from downwardly extended positions toward retracted positions, a chamber formed in said lower piston head communicating with said lower port and having restricted communication with the space between said cylinder barrel and said tubular body of said outer piston below the head, first and second passage means formed in said solid portion extending between said chamber and the interior of said tubular body of said outer piston, and first and second check valves in said first and second passage means, respectively, said first check valve being arranged to be closed while said second check valve is open and said second check valve open while said first check valve is closed depending upon said pistons being in retracted or extended positions and fluid being injected through said upper port or said lower port, said first and second passage means having communication with said chamber only while said outer piston is in its fully retracted position, normally engaged latch means operating between said outer piston and said lower cylinder head for locking said outer cylinder in its fully retracted position while said inner piston is in a retracted position, and latch operating means on said inner piston for releasing said latch means as said inner piston is moved into its fully extended position, so as to free said outer piston for movement toward the extended position.

4. A hydraulic cylinder comprising a closed cylinder barrel having ports opening through its upper and lower ends, a telescopic piston assembly within said barrel comprising a tubular outer piston and a solid inner piston, said outer piston comprising a head working in the bore of said barrel and a depending body concentrically spaced from the sidewalls of said barrel, and closure means closing the lower end of said tubular body portion, said inner piston comprising a piston body working in the bore of said tubular body and head of said outer piston and having a piston rod working through an accommodating opening formed in said closure means,

said upper part opening into the upper end of the bore of said tubular outer piston above said solid inner piston whereby injection of fluid under pressure through said upper port can drive said inner piston downwardly from an upwardly retracted position to reach its fullydownwardly extended position wherein said inner piston engages said closure'means of said outer piston in amanner to force said outer piston downwardly from its fully retracted position to its fully extended position, the lower end of said barrel being formed with a chamber communicating with said lower port and with the space between said barrel and said tubular body of said outer piston below its head, whereby fluidunder pressure injected through said lower port with said upper port acting as an exhaust portion can force said fluid to move said outer piston upwardly from its fully extended positionto its fully retracted position, and valved passage means in said closure means on the lower end of said outer piston arranged to have communication with said chamber in the lower cylinder head only while said outer piston is in its fully retracted position, said valved passage means being arranged to transfer fluid under pressure from said chamber to the interior of said'tubular outer piston beneath said solid inner piston while said outer piston is in' its fully retracted position, so as to move said solid inner piston upwardly from an extended position to a retracted position while fluid underpressure is being injected through said lower port, and normally engaged latch means operating between said outer piston and said lower end-of said barrel for positively looking said outer piston in its retracted position as said outer piston resumes its retracted position, and latch operating means on said solid inner piston for releasing said latch means to free said outer piston for movement tward an extended position as said inner piston is moved downwardly into its fully extended position by injection of fluid under pressure through said upper port.

JOHN A. CELENZA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 902,723 Gauer Nov. 3, 1908 1,130,884 Blakey Mar. 9, 1915 1,731,254 McNab Oct. 15, 1929 2,060,344 Perkins Nov. 10, 1936 

